Field
The present specification generally relates to optical fibers and, more specifically, to optical fibers for converting a Gaussian laser beam into a Bessel laser beam and laser delivery systems comprising the same.
Technical Background
Bessel laser beams may be desirable for material processing applications since a “perfect” Bessel laser beam does not diffract (spread out) as it propagates along a beam axis. Accordingly, when a Bessel laser beam is focused, the depth of focus can be more than ten times greater than for a conventional Gaussian laser beam. For example, a Gaussian laser beam with a 1.06 micrometers (μm) wavelength can be focused to about a 1 μm diameter focal spot and has a depth of focus of about 1 μm. In contrast, a Bessel laser beam having the same wavelength (1.06 μm) can achieve the same focal spot diameter (1 μm) and have a depth of focus of more than 10 μm. Such an increase in the depth of focus is desirable for laser characterization techniques, laser processing techniques, etc.
Conventional laser systems generate a Gaussian laser beam, which unlike a Bessel laser beam, diffracts while propagating along a beam axis. A Bessel laser beam may be generated or converted from a Gaussian laser beam using free-space optics systems such as an annular aperture, an axicon prism, or a combination thereof. However, free-space optics systems are bulky and have low alignment tolerances and high cost.
Accordingly, a need exists for alternative apparatuses for converting a Gaussian laser beam into a Bessel laser beam.